JP2003154453A - Method for producing can body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a can body with which development of gap corrosion is prevented and welding state can be visually confirmed. SOLUTION: The can body 1 is produced by welding from the inside while butting the peripheral edge part of a bowl-shaped first end plate 2 to the one end part 2 of a cylindrical barrel body 3 and further, by welding from the inside while butting the peripheral edge part of a bowl-shaped second end plate 4 having the opening part 7 at the top part to the other end part of the barrel body 3. Therefore, the development of the gap corrosion can be prevented and the welding state can be visually confirmed easily and this can body can reliably be used over a long term without developing defective welding.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a can used for an electric water heater, an electric water heater or the like. 2. Description of the Related Art Conventionally, in this kind, as disclosed in Japanese Patent Publication No. 2-44627, for example,
The peripheral edge of the first end plate is expanded outward and processed into a tapered shape,
One end of the cylindrical body is inserted into the inner peripheral surface, the ends are welded inward, and then the peripheral edge of the second bowl-shaped end plate is inserted into the other peripheral edge of the body and overlapped. By welding from the outside, variations in processing accuracy can be absorbed, the welding quality can be improved, and crevice corrosion of the welded portion inside the can body can be prevented. [0003] In the prior art, the second end plate and the body are welded from the outside after the peripheral portions thereof are overlapped with each other, and are not welded and come into contact with hot water. The inner end has the problem that the gap is corroded and water leakage occurs in a short period of time.In addition, since the welded portion is superimposed, it can be visually confirmed whether or not the welding has been performed. It could not be performed, and had a problem that it was finally found by a leak inspection in a later process. In order to solve the above-mentioned problems, the present invention focuses on this point. In particular, the present invention is made up of a peripheral end of a bowl-shaped first end plate and one end of a cylindrical body. And welded from the inside, and the other end of the body is abutted against the peripheral edge of a second end plate having a bowl-shaped opening at the top, and a welding torch is inwardly directed from the opening. The butt portion is inserted and welded from the inside. [0005] Since the welded portion is a butt weld, there is no overlapped portion and there is no risk of crevice corrosion occurring on the side opposite to the welded side.
Welding is performed from the inside directly in contact with hot water, so it is possible to reliably prevent water leakage due to corrosion.Furthermore, in the welding state, the molten metal leaks out from the butt gap and can be visually checked easily, and the subsequent process It is easy to understand without having to go to this point and can reduce welding defects. Furthermore, special welding jigs and devices can be made by welding the inside from the inside by abutting the other end of the body and the peripheral edge of the second end plate through the opening so that the welding torch can enter the inside. It is possible to easily provide a can body having a good welding state even without it. Next, a method for manufacturing a can according to the present invention will be described with reference to an embodiment shown in the drawings. Reference numeral 1 denotes a can body made of a ferritic stainless steel plate having a thickness of 0.8 mm to 1.2 mm for storing hot water in an electric water heater or the like, and the first end plate 2, the body 3, and the second end plate 4 are joined by argon arc welding. It is composed by doing. After the first end plate 2 is formed in a hemispherical shape by press working, the peripheral end is exposed by cutting.
And one end of the body 3 welded in advance and formed into a cylindrical shape;
After butting against the peripheral edge, the butting portion 5 is joined by argon arc welding from the inside with a torch 6. The second end plate 4 is formed in a hemispherical shape by press working, and a large-diameter opening 7 for a hot water supply pipe (not shown) to be attached in a later step is formed on the top, and then the peripheral end is formed. After the end portion is cut out by cutting, the other end of the body 3 to which the first end plate 2 is welded and the peripheral end portion are butted, and this butted portion 8 is welded through the opening 7 for welding. The torch 9 is put inside and joined by argon arc welding from the inside. Next, in the welding operation of each part, first, the first head 2 is held horizontally on the holder 10 of the welding machine (not shown), and then the body 3 held horizontally by the inner clamp 11 is moved. Then, the torch 6 is moved from the inside of the body 3 to the butted portion 5 of the first head 2 and the setting is completed. In this horizontal position, the butting portion 5 is argon arc welded from the inside by the torch 6 while the first end plate 2 and the body 3 make one rotation slowly and synchronously. On the opposite side, a shielding gas for cooling flows. In the next welding machine, the second end plate 4 is held horizontally by the holder 12 and then the outer clamp 13 is held.
The other end of the body 3 and the second end plate 4 are brought into contact with each other by moving the welded first end plate 2 and body 3 held horizontally to each other. Part 7
The torch 9 which has entered inside via the is positioned and the setting is completed. In this horizontal position, while the first end plate 2 and the body 3 are welded to each other and the second end plate 4 makes one rotation slowly in synchronization, the torch 9 moves the butted portion 8 from the inside. Argon arc welding is performed, and a cooling gas for cooling is also flowing on the opposite side. Therefore, the first and second important parts in the manufacture of the can 1
By welding the end plates 2, 4 and the body 3 from the inside by abutting, there is no need to worry about crevice corrosion because there is no overlapped portion as in the conventional case, and welding is performed from the inside that directly contacts hot water. As a result, water leakage due to corrosion can be reliably prevented and the product can be used with peace of mind.In addition, the welded state can be easily checked visually by the molten metal leaking out from the butt gap, until the subsequent process It is easy to understand without going and can reduce welding defects. In order to perform welding from the inside where the other end of the body 3 and the peripheral end of the second end plate 4 are abutted with each other, a welding torch 9 can be inserted into the inside through the opening 7. It is possible to easily provide the can body 1 having a good welding state without making any jig or device. Further, the welding between the first head plate 2 and the body 3 and the welding between the welded plate and the second head plate 4 are all performed in a horizontal state, so that the welding operation is performed in a horizontal state. The conveyor can be sent to the next operation, and an efficient production line that can be mounted on the machine immediately after taking it can be made, and large and heavy cans can be mass-produced in a short time. It is. In this embodiment, the welding is argon arc welding. However, the welding is not limited to this, and any welding suitable for stainless steel may be used. As described above, according to the present invention, since the welded portion is a butt weld, there is no overlapped portion, and there is crevice corrosion at a portion in contact with the hot water on the opposite side of the weld as in the prior art. There is no need to worry about this, and both the first and second heads
Welding is performed from the inside directly in contact with hot water, so it is possible to reliably prevent water leakage due to corrosion.Furthermore, in the welding state, the molten metal leaks out from the butt gap and can be visually checked easily, and the subsequent process It is easy to understand even without going to the point where welding defects can be reduced. Furthermore, special welding jigs and devices can be made by welding the inside of the other end of the fuselage with the peripheral end of the second end plate by allowing the welding torch to enter the inside from the opening. It is possible to easily provide a can body having a good welded state without it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a can body provided with an embodiment of the present invention. FIG. 2 is an explanatory view of a main part showing a welding state of the first end plate and the body. FIG. 3 is an explanatory view of a main part showing a welding state between the second end plate and the body. [Description of Signs] 1 can body 2 first end plate 3 body 4 second end plate 7 openings 5, 8 butted portions 6, 9 torch

Claims (1)

Claims: 1. A peripheral end of a first bowl-shaped end plate and one end of a cylindrical body are abutted and welded from the inside, and a bowl-shaped end is further provided on the other end of the body. A method for manufacturing a can body, comprising: butting a peripheral end of a second end plate having an opening at a top, inserting a welding torch inward from the opening, and welding the butted portion from the inside.